Pogo pins are often used in the testing of integrated circuit (IC) devices. IC packages typically have a number of contact pads, which serve as an interface or connection point to external circuitry. These contact pads are very small and delicate. Thus, a testing apparatus, used to test the function or performance of an IC device, must be able to make contact with one or more contact pads on the IC device without damaging the pads. Otherwise, the device may be rendered unusable for its intended purpose. The design and compressibility of pogo pins allow them to make contact with an IC device or a contact pad on the device.
FIG. 1 illustrates a prior art embodiment of a typical pogo pin. The pogo pin 100 is made up of two contact elements 110 and 120, held together by a spring 130 and a housing 140. The first contact element 110 is designed to make a secure contact with a contact pad of an IC device. The second contact element 120 can be connected to circuitry on a testing apparatus. The first and second contact elements 110 and 120 are electrically coupled together via the housing 140 to bridge a connection between the ends of the pogo pin 100 so that electrical signals can be transmitted between the testing apparatus and the IC device.
When the pogo pin 100 is sandwiched between an IC device and a testing apparatus, the spring 130 compresses to exert force on the contact pad of the IC device by the first contact element 110. However, in order to maintain an electrical connection between the IC device and the testing apparatus, the first and second contact elements 110 and 120 must remain in constant contact with the housing 140, regardless of the amount of compression or displacement caused by the force of contact with the underlying IC device. Accordingly, the first and second contact elements 110 and 120 must rub against the inner wall of the housing 140, creating contact resistance, as the pogo pin 100 is compressed and decompressed. The friction between the first and second contact elements 110 and 120 and the housing 140 causes wear and tear on the surfaces 150 where each of the first and second contact elements 110 and 120 makes contact with the housing 140. This, in turn, increases the contact resistance. Such wear and tear, along with the increased contact resistance, can reduce the signal quality transmitted by the pogo pin 100 over time.
Accordingly, there is a need for a compressible contact pin that can withstand continued use without loss of signal quality. More specifically, there is a need for a compressible contact pin comprised of frictionlessly connected contact elements, so that the contact pin can be compressed and decompressed without substantial wear and tear on its parts and/or increased contact resistance.
Like reference numerals refer to corresponding parts throughout the drawing figures.